Sildenafil dilates ophthalmic artery in type 2 diabetic patients

BACKGROUND: Conflicting reports exist on the effect of sildenafil on ophthalmic artery blood flow; many visual disturbances due to vascular insult were reported with the use of sildenafil in diabetic patients like nonarteritic ischemic optic neuropathy. OBJECTIVES: The present work aimed to investigate whether sildenafil modulates ophthalmic artery vasoreactivity in patients with type 2 diabetes mellitus. Literature reports on this aspect are lacking. METHODS: A total of 35 male subjects were enrolled in this study, 18 with type 2 diabetes mellitus matched with 17 normal individuals. Ophthalmic artery was insonated through a transorbital window using colored Doppler equipment with transcranial Doppler facility. Ophthalmic artery reactivity was assessed using breath holding/hyperventilation test, before and after giving 50 mg oral sildenafil. RESULTS: It was found that in both normal subjects and diabetic patients, sildenafil increased baseline control of mean flow velocity of ophthalmic artery significantly (p < 0.05), breath holding caused a decrease of MFV(opa) (p < 0.05), and subsequent hyperventilation caused increase of MFV(opa) (p < 0.05). There was no statistically significant change in breath holding index and full range of vasodilatation of ophthalmic artery (p > 0.05) after sildenafil, in normal and diabetic groups. There was a significant increase of resistive index of ophthalmic artery flow in diabetic patients compared with that of normal subject (p < 0.05). Sildenafil decreased resistive index of ophthalmic artery flow significantly only in diabetic patients (p < 0.05). CONCLUSION: Sildenafil increased MFV(opa), but had no significant effect on vasoreactivity of ophthalmic artery; sildenafil decreased resistive index only in type 2 diabetic patients.